Wash beet greens thoroughly to remove grit. Separate stems from leaves. Chop stems finely and roughly chop the leaves.
1 bunch beet greens
Zest the lemon, then juice half, removing any seeds. Save the remaining half for another use.
1 lemon
Heat olive oil in a large skillet over medium heat. Stir in garlic and red pepper flakes and cook for about 30 seconds, just until fragrant. Add chopped stems and cook for 2–3 minutes until slightly softened.